A Comparative Study of the Performance of Overhead Crane System Swing Angle Control

Abstract

An overhead crane is a type of heavy machinery capable of efficiently transporting ex tremely heavy loads. Due to their simple and compact structure, easy and flexible oper ation, fast delivery and convenient installation, reasonable design, and different slings for lifting to suit various situations, overhead cranes can raise, lower, and transport a large cargo through the overhead surface in a facility. However, due to the payload continuous oscillations caused by the low damping ratio during movement, manual con trol is difficult, reducing the accuracy and delaying overall positioning time. As being non-linear and under-actuated, the overhead crane system has two degree of freedom and one control input. The main target is to control the overhead crane system, and to improve the performance by eliminating the swing angle and reducing positioning error in order to increase productivity and reduce the safety hazard related to the presence of oscillatory heavy loads. To study and improve the overall performance of entire system, the model of the overall system is derived by considering the actuator, which is a Brush less DC Motor (BLDCM) in this thesis. In this regard, the performance characteristics of BLDCM for overhead cranes are studied. The control designs in this study to con trol and improve the performance of an overhead crane system are: A conventional Proportional Integral Derivative (PID) controller by using analytical pole placement technique, with a reasonable control theory; from self-adaptive PID control strategies, Fuzzy-PID (FPID) and Particle Swarm Optimization based PID (PSO-PID) control designs successfully performed the aim; and lastly, PI-Regulator which has a state vari able to design PI-Regulator as a state feedback is designed and successfully achieved the goal. The performance and robustness evaluations for each of designed controllers were done under different conditions using the MATLAB/ Simulink software tool for im plementation. Therefore, the time domain performance measures of controllers at the worst case, which means, when the maximum swing of the load is 10◦ = 0.175 rad , and with a disturbance added to the system, PID had a rise time, tr, of 0.3822 sec, a settling time, ts, of 5.3449 sec, and with a maximum overshoot, Mp, of 17.7099%; FPID with tr of 0.3800 sec, ts of 6.4918 sec, and Mp, 15.1083%; PSO-PID with tr of 0.2527 sec, ts of 2.1372 sec, and Mp of 5.2489%; Finally, PI-Regulator had tr of 2.4134 sec, ts of 4.6637 sec, and Mp 0% respectively. In general, the performance and robustness of each of the designed controllers for the system is evaluated, and compared under dis turbance and parameter uncertainty. Based on the time domain performance measures of controllers, the performance of overhead crane system is improved by reducing the swing angle, and maintaining an accurate positioning. In this thesis, PSO-PID control of overhead crane system had a best performance.